1 How It Works

rbenv operates on the per-user directory ~/.rbenv. Version names in
rbenv correspond to subdirectories of ~/.rbenv/versions. For
example, you might have ~/.rbenv/versions/1.8.7-p354 and
~/.rbenv/versions/1.9.3-rc1.

Each version is a working tree with its own binaries, like
~/.rbenv/versions/1.8.7-p354/bin/ruby and
~/.rbenv/versions/1.9.3-rc1/bin/irb. rbenv makes shim binaries
for every such binary across all installed versions of Ruby.

These shims are simple wrapper scripts that live in ~/.rbenv/shims
and detect which Ruby version you want to use. They insert the
directory for the selected version at the beginning of your $PATH
and then execute the corresponding binary.

Because of the simplicity of the shim approach, all you need to use
rbenv is ~/.rbenv/shims in your $PATH.

2 Installation

Compatibility note: rbenv is incompatible with rvm. Things will
appear to work until you try to install a gem. The problem is that
rvm actually overrides the gem command with a shell function!
Please remove any references to rvm before using rbenv.

2.1 Basic GitHub Checkout

This will get you going with the latest version of rbenv and make it
easy to fork and contribute any changes back upstream.

Check out rbenv into ~/.rbenv.

$ cd
$ git clone git://github.com/sstephenson/rbenv.git .rbenv

Add ~/.rbenv/bin to your $PATH for access to the rbenv
command-line utility.

$ echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bash_profile

Zsh note: Modify your ~/.zshenv file instead of ~/.bash_profile.

Add rbenv init to your shell to enable shims and autocompletion.

$ echo 'eval "$(rbenv init -)"' >> ~/.bash_profile

Zsh note: Modify your ~/.zshenv file instead of ~/.bash_profile.

Restart your shell so the path changes take effect. You can now
begin using rbenv.

$ exec $SHELL

Install Ruby versions into ~/.rbenv/versions. For example, to
install Ruby 1.9.2-p290, download and unpack the source, then run:

2.2 Homebrew on Mac OS X

You can also install rbenv using the
Homebrew package manager on Mac OS
X.

$ brew update
$ brew install rbenv
$ brew install ruby-build

The same commands can be used for upgrading.

Afterwards you'll still need to add eval "$(rbenv init -)" to your
profile as stated in the caveats. You'll only ever have to do this
once.

2.3 Neckbeard Configuration

Skip this section unless you must know what every line in your shell
profile is doing.

rbenv init is the only command that crosses the line of loading
extra commands into your shell. Coming from rvm, some of you might be
opposed to this idea. Here's what rbenv init actually does:

Sets up your shims path. This is the only requirement for rbenv to
function properly. You can do this by hand by prepending
~/.rbenv/shims to your $PATH.

Installs autocompletion. This is entirely optional but pretty
useful. Sourcing ~/.rbenv/completions/rbenv.bash will set that
up. There is also a ~/.rbenv/completions/rbenv.zsh for Zsh
users.

Rehashes shims. From time to time you'll need to rebuild your
shim files. Doing this on init makes sure everything is up to
date. You can always run rbenv rehash manually.

Installs the sh dispatcher. This bit is also optional, but allows
rbenv and plugins to change variables in your current shell, making
commands like rbenv shell possible. The sh dispatcher doesn't do
anything crazy like override cd or hack your shell prompt, but if
for some reason you need rbenv to be a real script rather than a
shell function, you can safely skip it.

Run rbenv init - for yourself to see exactly what happens under the
hood.

3 Usage

Like git, the rbenv command delegates to subcommands based on its
first argument. The most common subcommands are:

3.1 rbenv global

Sets the global version of Ruby to be used in all shells by writing
the version name to the ~/.rbenv/version file. This version can be
overridden by a per-project .rbenv-version file, or by setting the
RBENV_VERSION environment variable.

$ rbenv global 1.9.2-p290

The special version name system tells rbenv to use the system Ruby
(detected by searching your $PATH).

When run without a version number, rbenv global reports the
currently configured global version.

3.2 rbenv local

Sets a local per-project Ruby version by writing the version name to
an .rbenv-version file in the current directory. This version
overrides the global, and can be overridden itself by setting the
RBENV_VERSION environment variable or with the rbenv shell
command.

$ rbenv local rbx-1.2.4

When run without a version number, rbenv local reports the currently
configured local version. You can also unset the local version:

$ rbenv local --unset

3.3 rbenv shell

Sets a shell-specific Ruby version by setting the RBENV_VERSION
environment variable in your shell. This version overrides both
project-specific versions and the global version.

$ rbenv shell jruby-1.6.4

When run without a version number, rbenv shell reports the current
value of RBENV_VERSION. You can also unset the shell version:

$ rbenv shell --unset

Note that you'll need rbenv's shell integration enabled (step 3 of
the installation instructions) in order to use this command. If you
prefer not to use shell integration, you may simply set the
RBENV_VERSION variable yourself:

$ export RBENV_VERSION=jruby-1.6.4

3.4 rbenv versions

Lists all Ruby versions known to rbenv, and shows an asterisk next to
the currently active version.

rbenv rehash creates or removes shims only when necessary instead
of removing and re-creating all shims on each invocation.

Fixed that RBENV_DIR, when specified, would be incorrectly
expanded to its parent directory.

Removed the deprecated set-default and set-local commands.

Added a --no-rehash option to rbenv init for skipping the
automatic rehash when opening a new shell.

0.2.1 (October 1, 2011)

Changed the rbenv command to ensure that RBENV_DIR is always an
absolute path. This fixes an issue where Ruby scripts using the
ruby-local-exec wrapper would go into an infinite loop when
invoked with a relative path from the command line.

0.2.0 (September 28, 2011)

Renamed rbenv set-default to rbenv global and rbenv set-local
to rbenv local. The set- commands are deprecated and will be
removed in the next major release.

rbenv now uses greadlink on Solaris.

Added a ruby-local-exec command which can be used in shebangs in
place of #!/usr/bin/env ruby to properly set the project-specific
Ruby version regardless of current working directory.

Fixed an issue with rbenv rehash when no binaries are present.

Added support for rbenv-sh-* commands, which run inside the
current shell instead of in a child process.

Added support for storing rbenv versions and shims in directories
other than ~/.rbenv with the $RBENV_ROOT environment variable.

Added support for debugging rbenv via set -x when the
$RBENV_DEBUG environment variable is set.

Refactored the autocompletion system so that completions are now
built-in to each command and shared between bash and Zsh.

Added support for plugin bundles in ~/.rbenv/plugins as documented
in issue #102.

Added /usr/local/etc/rbenv.d to the list of directories searched
for rbenv hooks.

Added support for an $RBENV_DIR environment variable which
defaults to the current working directory for specifying where rbenv
searches for local version files.

0.1.2 (August 16, 2011)

Fixed rbenv to be more resilient against nonexistent entries in
$PATH.

Made the rbenv rehash command operate atomically.

Modified the rbenv init script to automatically run rbenv
rehash so that shims are recreated whenever a new shell is opened.

Added initial support for Zsh autocompletion.

Removed the dependency on egrep for reading version files.

0.1.1 (August 14, 2011)

Fixed a syntax error in the rbenv help command.

Removed -e from the shebang in favor of set -e at the top of
each file for compatibility with operating systems that do not
support more than one argument in the shebang.

0.1.0 (August 11, 2011)

Initial public release.

4.2 License

(The MIT license)

Copyright (c) 2011 Sam Stephenson

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.